Patent GB-552231-A (GB)
Title: Improvements in or relating to timers for x-ray photographic apparatus
IPC: G03B42/02
Filed: 1941-09-26
Abstract: 552,231. Radiographic apparatus; actuation of switches. COX, Ltd., S., and EWIN, R. L. H. Sept. 26, 1941, No. 12488. [Class 98 (i)] [Also in Group XXXVII] A timer for radiographic apparatus comprises a notched timing disc initially adjustable to time the exposure, motor-driven gears for rotating the disc, and a solenoid energized on operation of a push-button to control the operation of the gears and to cause a lever to engage the timing disc to control the period of operation of the tube during which the image on a fluorescent screen is photographed. The apparatus shown automatically causes the energization of the X-ray tube or a predetermined time, the subsequent switching on and off of a lamp which illuminates a card containing particulars of the patient whilst it is photographed on the .same section of film, and the winding on of the film. Fig. 1 shows a front, and Fig. 3 a sectional elevation. The exposure time is pre-set by rotary adjustment of a timing-disc 25 by means of a gear 33 on which is a stop pin 35 with which a pin 36 on the disc is held in engagement by a coiled spring 37, which tends to turn the disc clockwise. The gear 33 is rotated through gears 34, 32 from a shaft 31 carrying a setting-knob and a pointer 15 indicating against a scale 14. The shaft 17 carrying the disc is divided a sleeve 26 carrying a brake drum 27 and a crown gear 22 being rotatably mounted on the forward portion and a crown gear 21 being secured to the rear portion. A planet wheel 23 engaging the crown wheels 21, 22 is pivoted on a sleeve secured to the forward portion of the shaft 17. The crown wheel 21 is driven through gearing from a synchronous motor M, and drives the wheels 23, 22 idly as long as the latter is free to rotate. When an exposure is to be made, a starting switch B, Fig. 10, is closed, energizing an electromagnet S which rocks the pivoted spring-retracted armature 41 to the position shown. A brake lever 46, Fig. 3, pivoted at 47 and normally raised by a roller 45 on a bracket 44 carried by the armature, is thereby lowered on to the brake wheel 3 and locks the crown wheel 22. The planet wheel 23 now rolls on the wheel 22 and rotates the shaft 17 of the timing- disc 25. Simultaneously, a roller 49 on the armature co-operating with a ramp 50 on a bell-crank lever 51 is lowered, allowing the lever to rock under the action of a spring 58 to bring a pin 54 into contact with the periphery of the timing disc. An insulated pin 60 on the armature at the same time closes the contacts of switches 1, 3, Fig. 10, the latter of which shorts the starting switch B so that the operation will continue if the latter is released. The lever 51 carries rollers 66, 67 controlling switches 2, 4 respectively, the former switch being closed and the latter open when the lever is in the position shown in Fig. 1. The energizing circuit of the tube, which is connected at X, Fig. 10, is now completed through the switches 1, 2 and the exposure continues until a shoulder 55 on the disc 25 passes the pin 54, allowing the lever 51 to rock further anticlockwise. In doing so, it opens the switch 2 and closes the switch 4, so terminating the X-ray exposure and completing the circuit of the lamp P through the switches 4 and 1. This lamp illuminates the patients' card for a fixed period, at the end of which a notch 57 reaches the pin 54, allowing a still further rocking movement of the lever 51. This results in opening the switch 4, so extinguishing the lamp P, and in causing a projection 74 on the lower end of the lever to open switch contacts 5, de-energizing the motor M, and to close contacts 6, energizing a solenoid C which effects the movement of the film through the mechanism described in Specification 538,995, [Group XXXVI]. This mechanism then opens a switch 7 so that if the switch B has been opened, or when it is opened, the solenoid S is de-energized, and the switches all return to their initial positions. Specification 538,981 also is referred to.